Mystery Malady Kills More Bees, Heightening Worry on Farms

For America’s beekeepers, who have struggled for nearly a decade with a mysterious malady called colony collapse disorder that kills honeybees en masse, the last year was particularly bad.

A mysterious malady that has been killing honeybees en masse for several years appears to have expanded drastically in the last year, commercial beekeepers say, wiping out 40 percent or even 50 percent of the hives needed to pollinate many of the nation’s fruits and vegetables.

A conclusive explanation so far has escaped scientists studying the ailment, colony collapse disorder, since it first surfaced around 2005. But beekeepers and some researchers say there is growing evidence that a powerful new class of pesticides known as neonicotinoids, incorporated into the plants themselves, could be an important factor.

The pesticide industry disputes that. But its representatives also say they are open to further studies to clarify what, if anything, is happening.